This invention relates to new and useful improvements in agricultural injection sprayers and particularly to a method of setting the desired rate of chemical application to suit the chemical being utilized.
Conventionally, the operator of an injection system adjusts the rate of chemical application in one of two ways:
(1) By using charts and/or graphs, the corresponding indices of the machine are ascertained, i.e. where a flow meter ball should be located, etc. and then the machine is set to these indices;
(2) By inputting the rate directly into a monitor in the cab by either a thumb wheel system where the numbers are manually rolled into their proper position, or electrically by pushing buttons until the rate on the display equals the desired rate.
The first method is, of course, lengthy, cumbersome and prone to misorientation and error.
The second system is an improvement and gives the appearance initially of being the optimum solution to assuring the proper rate of chemical application. How ever, several factors enter into the second system indicating that this system is not as advantageous as initially believed.
Firstly, the units of measurement vary to such a degree that there exists three systems in use today in Western Canada, namely Metric, Imperial and "bastard" (liters/acre).
Secondly, conversion may be required if the monitor demands Imperial measure and only Metric information is found on the container or, if the monitor can accept all three systems, the switch may be on "Metric" when the operator believes it is on "Imperial". It will therefore be appreciated that conversion of any kind by the operator is prone to error.
Thirdly, the operator may read the rate from the chemical container, but as it is rarely possible to take the container with him inside the cab, memory is relied upon to input the proper numbers and this is awkward and difficult to check.
Fourthly, to input information into a monitor correctly usually requires a certain procedure to prevent inadvertent input or change of the input information. Errors may occur including incorrect registration of numbers or information placed in the wrong location. If programming is direct as with the thumbwheel system, the rate of application may be changed inadvertently during operation, again relying on memory to signal that the input information is now correct.
A third system type is described in Coffee et al U.S. Pat. No. 4,553,702 where, in an injection sprayer, the chemicals to be sprayed are supplied in special containers equipped with pre-coded electronic memory chips that are interrogated by a microprocessor controlled sprayer control system. Included in the information coded on the chip are acceptable application rates for the chemical This is a very complex piece of equipment and, in the preferred embodiment, it still requires the operator to select the application rate using a manual push button control.
The present invention is concerned with an alternative form of application rate control.